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Wednesday, July 20, 2011

Mandelbulb 3D Tutorial: Render Quality (those damn pixels!)

Alrighty! I'm slowing down with my posts and to all who missed me, my apologies! ... I've had this Mandelbulb 3D tutorial in my head so I forgot a little that this is a blog and I can (and should) post about anything, in between tutorial pages :)

So I'll do that - but for now, I'm going to share with you my discovery of how to improve the state of your fractal if it's full of annoying little noisy pixels. As an example, I zoomed into an appropriate area using the Amazing Box formula, with lots of pixelation happening along the edges and in various spots, etc.

Now before I start, let me tell you this: The better you want your image to look like, the longer it will take to render. As I'm sure you already know, when you use the "preview" mode to render, it goes quickly, but the image is often riddled with pixels. As you go up in quality, using the "Video", "Mid" and "High" modes, renders take longer but the pixels start disappearing into nice smooth satisfying surfaces/curves.

(Something to note is that, sometimes (really, not always) a render with "High" mode comes out looking very different (and usually much better-looking) than in "Preview" mode. So do not give up after "Viewing to Main" once. Try Video and Mid, see if the fractal changes for the better, etc)

Something else very important to note is that often, as I'm sure you've already encountered, what you see in the Navigator window is not all what comes out in the Render window. This is just one of those things... Sometimes, it'll just be the colouring that's different, and sometimes, it's the whole shape of everything, as is the case with the example I used for this Tut page. In fact, let me start here. I said I used Amazing Box:

Zoom somewhere in Amazing Box in navigator window - 20 iterations
But then, when I clecked on view to main, and rendered the bugger in preview mode, I got this:



The above image, rendered in Preview mode

Not very nice, you know. Still, what can we do to this to improve it a little? I tried simply rendering it in "Mid" mode:


Aha! Much better, even if not good yet. So now, have you noticed the numbers changing in the little "Calculations" tab every time you changed from one mode to another? From Preview to Mid, for example. I decided I wanted to try changing them myself instead of choosing "High" .. So I kept it on "Mid" and just changed the Raystep multiplier and Stepwidth limiter values (see image below).


I changed them from the values above to 0.1 and 0.1 (which are even lower than the default settings of High Mode) and got this:



Much better! But still rather visible pixelation... If we lower the values even more, say 0.05 for both of them.. :


Almost there! The pixels are STILL visible though. So I dropped the values even lower, to 0.02. :


And voila! No pixels. But remember:

The lower you go with those two values, the longer the render is going to take. My first render of the above image in Mid mode took only a few seconds, whereas the above one took around 12 minutes. So if you have some awesome fractal image loaded, at 4000x3000 resolution, and try rendering it with Raystep Multiplier and Stepwidth limiter at 0.02, expect to wait a very long time for your render! ... I tried it, and ended up with something that took 21 hours!

The good news is that my above example here I chose for this tutorial page exactly because it had a lot of pixelation. This is truly not always the case. Most of the time you'll probably only have a little bit, so then you can lower the values little by little, until you're happy with the quality. If some pixels persist but you really don't want to wait for another long render, then Photoshop to the rescue! Manually sorting out those pixels can often be a much easier solution.


If my tutorial is helping you, please consider supporting me over at my Patreon page.
I also have a deviantArt gallery.


Next Mandelbulb 3D tutorial : Julia Mode

11 comments:

  1. As usual, invaluable information for anyone interested in creating truly excellent Mandelbulb3D images.

    Stray pixels are the scourge of nearly all fractal programs, and here you have shown us how to combat this problem.

    Thanks again !

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  2. And once again, I'm so glad you enjoyed it =) ... Please feel free to add any new insights, should you discover any, as you explore Mandelbulb 3D yourself.

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  3. I shall thank you too! Now I only wish I had Xeon...

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  4. Thank you so much! This is the info I was looking for :-)

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  5. My pleasure, Annemieke and Taavi =) You'll both probably notice that I haven't worked much on this blog. Please forgive me. My life is very busy and moreover, I don't even have a PC right now! Mine died =(

    But with my new one, I'm going to be all inspired to see what my new processor can do in terms of rendering =D ... So, no promises, but watch this space...

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  6. Wonderful info!! Thanks so much for posting this. I think my renders should improve and now I know what to tweak and how.

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  7. My pleasure, Peggi! =) I'm just amazed that my tutorials are still helping people ^^ I did these more than two years ago. I miss all this... 'Think I'm going to start trying to make videos and posting them on my youtube channel =)

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  8. Tried this on a render just now.... took longer... and the image got so dark it almost turned black-- with multiplier value of .05 and stepwith Limiter..0.02.. Still nooise all over the place too though! worse than otiginal render at default settings in fact... going the other way now...

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  9. ..confirmed here... actually getting better results and less pepper pushing up the values.. (Reminds me a bit this of rendering in Apo.. some renders required bigger values depending on the type of flame... others smaller...

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  10. All your tutorials assume an exoert level or advanced level - where do I find help for the beinner who wants tolearn how to use it? We are advanced as you are and when you start off the video with advanced material we have to quit.

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